Conventional microdermabrasion procedures exfoliate skin to improve the appearance of skin, remove skin abnormalities, and otherwise treat skin. Conventional microdermabrasion equipment can deliver a flow of crystals (e.g., aluminum oxide or alumina crystals) to abrade the epidermis. A vacuum pump compressor draws the crystals through a conduit and into a hollow handpiece held against a patient's skin. The crystals then strike the epidermis to abrade the skin. The crystals are removed via a suction tube connected to the handpiece. The crystals are then collected in a container. Unfortunately, it may be difficult to adjust the level of abrasion, crystals can clog lines, and crystals can damage equipment components, such as flow lines. Other conventional vacuum-based handpieces have abrasive rings at one end of a hollow tube. Vacuum pumps provide a low pressure to draw the patient's skin against the abrasive ring. Dislodged skin cells, which are located within an opening defined by the abrasive ring, are drawn through the hollow tube via the vacuum. It is difficult to manually control the level of pressure applied to the skin because of the constant vacuum, thereby making it difficult to control the level of abrasion. If the vacuum level is too high, the patient can experience painful abrasion of the skin.